1. Field of the Invention
The present invention generally relates to a load break interrupter for suppressing arcing during opening of a blade-type disconnect switch and, more particularly, is concerned with such an interrupter having a vented muffler assembly on an arc-suppressing tube.
2. Description of the Prior Art
In the use of high voltage electrical transmission and distribution equipment, it is common practice to provide manually operable blade-type switches which can be opened as needed to break the flow of current in order that linemen can work on such equipment. These switches employ a pivotally movable blade-like contact electrically connected between a pair of fixed switch terminal contacts. When the movable contact of the switch is swung open by means of a conventional hot-line tool or the like, the circuit between the fixed terminal contacts is broken and the flow of current is interrupted. The fixed and movable contacts are in proximal relationship during opening and closing of the movable contact and the swinging movement of the movable contact away from the fixed contacts is slow relative to the current flow.
Because transmission and distribution lines carrying high voltages on the order of 15,000 volts or more will produce arcing which is damaging to the blade-type switch as the movable contact is swung away from the fixed contacts, it is also common practice to employ load break interrupters with such blade-type switches. One load break interrupter marketed under the trademark DuoGap by Hubbell Power Systems, Inc. of Centralia, Mo., a subsidiary of Hubbell Incorporated, is designed to overcome the problems associated with arcing across switch contacts. The Hubbell DuoGap interrupter is illustrated and described in detail in U.S. Pat. No. 4,013,852 to Roberts et al. The Hubbell DuoGap interrupter basically includes a case, an arc-suppressing tube supported on the housing, a reciprocal shunt circuit rod slidably supported in the tube, electrical contacts spaced apart from one another on the rod and tube, and a spring-loaded trip mechanism disposed in the housing and coupled with the rod. Actuation of the trip mechanism pushes the rod through and relative to the tube to break an electrical shunt circuit between the electrical contacts on the rod and on the tube after the movable contact of the blade-type switch has separated from the fixed contacts thereof. Any arcing between the spaced apart electrical contacts on the interrupter rod and tube is confined to and suppressed inside the tube due to the presence of arc-suppressing material therein. The interrupter also includes a mechanism for resetting the interrupter to re-establish the shunt circuit through the interrupter after each actuation thereof.
The above-described Hubbell interrupter has performed highly satisfactorily over a prolonged period of commercial use. However, as with any successful product, the need arises from time to time to make improvements which will enhance its overall manufacture and operation.